Mobile computing devices or portable computers, such as laptop computers, have become increasingly popular. Mobile computing devices are battery powered in order to enhance their portability. A battery powered laptop computer operates for an extended period of time under battery power before the battery is either recharged or replaced. Alternatively, the mobile computing device may be powered from an external power source, such as an alternating current (AC) power source. As processor speeds and memory capacities of mobile computing devices have increased, so has their power consumption. At the same time, mobile computing devices have become increasingly smaller in size and weight.
It is important to reduce power consumption within an electronic circuit of the laptop computer, in order to extend the period of time during which the electronic circuit operates before recharging or replacing the battery. Known techniques disable power or disable clock signals (e.g., in a “sleep” or idle mode) to the electronic circuit in response to a specific time elapsing without sensing a particular type of activity. As such, it is desirable to limit the battery size within the mobile computing device.
Processor and memory bus clock speed corresponds directly to the amount of power required by the mobile computing device. Specifically, a faster clock speed results in increased power consumption, and a slower clock speed results in decreased power consumption. As such, most laptop computers are built with a clock speed which is much slower than similarly sized desktop computers, in order to reduce the power consumption and extend the amount of time that the laptop computer can be powered by a battery. It is desirable to have a mobile computing device which operates at a slower clock speed while battery powered, but is capable of operating at a higher clock speed when connected to an external (e.g., AC) power source.